Collapsible stroller

ABSTRACT

A collapsible child&#39;s stroller with a handle frame ( 30 ), a front wheel frame ( 10 ) and a rear wheel frame ( 20 ), mutually connected at a hinge joint ( 12, 22, 42 ) for mutual angular displacement between folded and unfolded configurations. The hinge joint has two spaced apart, parallel hinge axes, about which the frames ( 10, 20, 30 ) mutually rotate. The stroller is further provided with a locking element ( 43, 44 ) moveable between a locked position in which the frames ( 10, 20, 30 ) are locked in the unfolded configuration, and an unlocked position allowing the frames ( 10, 20, 30 ) to rotate to the folded configuration. The locking element ( 43, 44 ) moves in a direction traverse to the parallel hinge axes to better transfer loads between the frames.

FIELD OF THE INVENTION

The present invention relates to strollers for babies, toddlers andyoung children. In particular, the invention relates to strollers withcollapsible frames that fold into a compact configuration for storageand portability.

BACKGROUND OF THE INVENTION

Strollers are a well known and common way of transporting babies oryoung children. However, due to their size, strollers typically havecollapsible frames that fold into a more compact configuration forstorage or to be stowed in a vehicle.

In an effort to achieve a more compact folded configuration, somecollapsible strollers have particularly complex hinged and telescopicframe structures. While this may provide a compact folded form, thecomplexity of the frame increases the production costs. Furthermore,added complexity of the frame tends to weigh against a smooth andreliable folding mechanism. For parents of young children, thisoperation needs to occur as quickly and simply as possible.

Many countries have official design standards and regulations that applyto strollers. These require the frame to meet certain strength andrigidity thresholds while avoiding hazards such as finger traps and soon. The strength requirement specified by the official standards meanthat steel or aluminium alloy are the traditional choices for framematerial. However, from the perspective of material costs andhigh-volume production, polymer frames would be more desirable. Polymershave the added advantage of being lightweight, easily moulded intoergonomic shapes and coloured for greater aesthetic appeal. However, tomeet the required strength and structural standards, the polymer wouldneed to be an exotic composite and prohibitively expensive.Alternatively, a cheaper (and weaker) polymer would need to be formed inlarge cross sections which defeats the purpose of a compact collapsiblestroller.

With these issues in mind, there is a need for a collapsible strollerwith a predominantly polymer frame that meets the high strength andstructural requirements of the official standards, while smoothly,simply and reliably collapsing into a compact folded form.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a collapsible strollercomprising:

-   -   a handle frame;    -   a front wheel frame;    -   a rear wheel frame; and    -   a hinge joint connecting the handle frame, the front wheel frame        and rear wheel frame for mutual angular displacement relative to        each other about two spaced parallel hinge axes, the hinge joint        having a locking element moveable between an unlocked position        allowing the handle, front wheel and rear wheel frames to        mutually rotate into a folded configuration, and a locked        position in which the handle, front wheel and rear wheel frames        are fixed in an unfolded configuration; wherein,    -   the locking element moves in a direction transverse to the two        parallel hinge axes.

Preferably, the handle, front wheel and rear wheel frames arepredominantly polymer.

The Applicant has found that configuring the locking element such thatits movement is transverse to the hinge axes allows the locking elementitself to be a significant structural element of the stroller and inparticular the main folding hinge. This allows the stroller to bepredominantly polymer with reinforcement at a structurally crucial part.

The locking element can take a variety of forms, but is convenientlyprovided as a locking pin for ease of production and incorporation intothe hinge joint. Traditionally, the main hinge mechanisms in collapsiblestrollers use a locking pin or equivalent structure which moves parallelto the hinge axis to lock two hinged frame members together. This isadequate for preventing relative rotation of two frame elements but doesvery little to transfer bending or axial loads between these elements.By configuring the locking pin such that it extends in a directiontransverse to the hinge axis, it essentially becomes a significant loadbearing element in its own right. In particular, it provides a loadbearing element at the connection between two frame elements to transfersubstantial loads therebetween. As the locking pin is transverse to thehinge axis, it can also be made physically larger and stronger withoutany impact on the overall size of the frame elements as it stillcomfortably fits within the frame element cross-sections.

Preferably, the locking pin is metallic and in a particularly preferredform the locking pin is steel. Preferably the locking pin has a minimumcross sectional dimension of 5 mm. Preferably, the locking pin is solid,as tubular locking pins would risk being crushed. Preferably the lockingpin is at least 40 mm long and more preferably at least 55 mm long.

Preferably, the hinge joint has at least two reinforced bearing surfacesadjacent the locking pin when in the locked position, such thatstructural loads are transferrable between the reinforced bearingsurfaces via the locking pin. In some options, the hinge joint has metalaxles such that at least one of the reinforced bearing surfaces isprovided by one of the metal axles.

In another option, the reinforced bearing surface is provided by amovable element that moves into a load bearing position as the lockingpin moves to the locked position and moves away from the load bearingposition when the locking pin retracts from the locked position.

Preferably, the hinge joint has a hinge housing of polymer materialintegrally formed with the polymer rear wheel frame, and the polymerhandle frame has an integrally formed spur-gear formation for rotationabout one of the hinge axles within the hinge joint, while the frontwheel frame has an integrally formed polymer spur-gear formationrotatably mounted at the other of the hinge axles for meshinginter-engagement with the spur-gear formation of the handle frame.Preferably, the locking pin slides within a groove partially defined bythe handle frame and partially defined by the front wheel frame.Preferably, the groove is partially defined within the spur-gearformation of the handle frame and partially defined within the spur-gearformation of the front wheel frame such that the section of the groovein the front wheel frame aligns with the section of the groove in thehandle frame when in the locked position. Preferably the locking pin isbiased into the locked position, by a spring within the section ofgroove defined by the handle frame.

Preferably the hinge joint has a pin guide surface for slidingengagement with a distal end of the locking pin as the stroller foldsand unfolds such that the pin guide surface limits movement of thelocking pin when moving from the folded to the unfolded configuration.In a particularly preferred form, the front-wheel frame has a slidesurface for receiving the end of the locking pin from the pin guidesurface, and smoothly directing the locking pin to the section of thegroove in the front-wheel frame that partially defines the lockedposition. Preferably, the pin guide surface and the slide surface have acommon tangent at the point of transition where the pin guide surfacehands-off the end of the locking pin to the slide surface. In aparticularly preferred form, the locking pin is chamfered or rounded.

Preferably, the handle frame has a grip section and an unlockingactuator connected to the biased locking pin for retracting the lockingpin into the unlocked position. Preferably, the direction of movement ofthe locking pin and the longitudinal extent of the handle frame areangled relative to each other by less than 45 degrees such thatactuation of the unlocking actuator is a manual displacement in adirection broadly similar to the direction of movement of the lockingpin.

In a particularly preferred form, the longitudinal extent of the handleframe, the rear-wheel frame and the front-wheel frame are substantiallyparallel in the folded configuration.

Preferably, the front-wheel frame has a front-wheel assembly and therear-wheel frame has a rear-wheel assembly, the front-wheel assemblyhaving a narrower wheel base than the rear-wheel assembly such that inthe folded configuration, the front wheel assembly nests within therear-wheel assembly.

In a related aspect, the handle frame, the rear-wheel frame and thefront-wheel frame are formed from a glass fibre reinforced nylonmaterial. Preferably, the glass fibre reinforced nylon material is acomposite with 25% to 35% by weight of glass fibre.

In some embodiments, the rear wheel frame includes a braking mechanismto prevent rotation of the rear wheels, the rear wheel frame furthercomprising a brake actuator pedal configured for foot actuation of thebrake mechanism such that the pedal can be moved between an engaged anddis-engaged position using the sole of the foot only. It will beappreciated that this prevents scuffing to the upper parts of anyfootwear or injury and discomfort to those with open toed footwear.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example only with reference toa preferred embodiment illustrated in the accompanying drawings, inwhich:

FIG. 1 is a perspective of a collapsible stroller with child seat andhood fabric removed for clarity;

FIG. 2 is an exploded perspective of the collapsible stroller of FIG. 1;

FIG. 3 is an enlarged exploded perspective showing the top and left ofthe left-side hinge joint;

FIG. 4 is an enlarged exploded perspective showing the bottom and leftof the left-side hinge joint;

FIG. 5 is a longitudinal sectional view through the hinge joint in theunfolded configuration with locking pin in the locked position;

FIG. 6 is an exploded perspective of the underside of the rear wheelframe in isolation;

FIG. 7 is an enlarged perspective of inset A shown in FIG. 6;

FIG. 8 is an exploded perspective of the top of the rear wheel frame inisolation;

FIG. 9 is an enlarged perspective of inset B shown in FIG. 8;

FIG. 10 is an exploded perspective of the top side of the front wheelframe in isolation;

FIG. 11 is an enlarged perspective on inset C shown in FIG. 10;

FIG. 12 is an exploded perspective of the underside of the front wheelframe in isolation;

FIG. 13 is an enlarged perspective of inset D shown in FIG. 12.

FIG. 14 is a perspective of the stroller in the unfolded configurationtogether with the child seat, retractable hood and cup holder; and

FIG. 15 is a perspective of the stroller shown in FIG. 14 collapsed intothe folded configuration.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, the collapsible stroller is shown (without childseat, harness and hood fabric) in its unfolded configuration, a frontwheel frame 10, rear wheel frame 20 and handle frame 30 connect at apair of hinge joints 40. The complete stroller with child seat 80,fabric-covered retractable hood 82, and cup holder 84 is shown in theunfolded and folded configurations in FIGS. 14 and 15 respectively. Afabric seat 80 with restraint harness 86 suspends from the handle frame30 and the front wheel frame 10. Retractable hood 32, 82 provides shadewhen necessary. The front wheel frame 10 has a front wheel assembly 11with two castors 113 and 114 mounted for rotation about vertical axesfor steering and maneuverability. The rear wheel frame 20 has a rearwheel assembly 21 with larger diameter wheels 211 for ride comfort and abrake assembly (described below with reference to FIGS. 6 and 7). FIG. 2separates the frames and reveals the internal elements of the hingejoints 40. It will be appreciated the left and right hinge joints aremirror images so the description of the left hinge joint (see FIGS. 3, 4and 5) applies equally to both.

The rear wheel frame 20 has two integrally formed hinge housings 22.Each hinge housing has a pair of spaced metal axles 41 and 42. As bestshown in FIG. 4, the front wheel frame 10 is mounted for rotation aboutone of the axles 42 while the handle frame 30 is rotatably mounted tothe metal axle 41. The handle frame 30 and the front wheel frame 10 eachhave integrally formed spur gear formations 121 and 311 respectively.The teeth of the gear formations 121 and 311 mesh to control therotation of the handle frame 30 and the front wheel frame 10 relative tothe rear wheel frame 20.

As best shown in FIG. 5, the handle frame 30 and the front wheel frame10 combine to make groove 313 and 122 in which a locking pin 43 slidesbetween an unlocking and locking position. The locking pin 43 is in theunlocking position when it is within the groove section 313 defined bythe handle frame 30. In the locking position, the locking pin 43 ispartially in the groove section 122 defined by the front wheel frame 10and partially in the groove section 313 in the handle frame 30 as shownin FIG. 5. Spring 44 biases the locking pin 43 into the lockingposition.

In the locking position, the frames are secured in the unfoldedconfiguration. However, the locking pin 43 not only prevents relativerotation of the handle, front wheel and rear wheel frames, it provides ahigh strength structural element for transferring loads between each ofthe frames. To enhance this, metal pin 221 and metal axle 42 providere-enforced bearing surfaces positioned so that bending and axial loadstransfer between them via the locking pin 43.

As a load bearing element within the frame, the locking pin 43 is an 8mm square stainless steel rod. The pin length extends between the twoaxles or re-enforced bearing surfaces. It will be appreciated that thelocking pin can be different materials and adopt a variety ofconfigurations, but for practical purposes, the locking pin isconveniently metallic and has a minimum cross-sectional dimension of 4mm and a minimum length of 40 mm.

Referring to FIGS. 3, 4 and 5, the metal pin 221 is closely adjacent themetal axle 41 such that loads from both the front and rear wheel frames(10 and 20) transfer to each other, and the metal axle 42 of the handleframe 30 through the locking pin 43. The added strength and rigidityprovided by the locking pin 43 allows the polymer parts of the hingejoint 40 to be smaller and more compact.

Smooth and reliable folding and unfolding of the stroller is importantto users. To facilitate this, the hinge joints have a pin guide surface312 on the hinge housing 22 which co-operates with slide surface 12 onthe front wheel frame 10. In the folded configuration, the end of thelocking pin 43 is pressed against the pin guide surface 312 by thecompressed spring 44. As the stroller is unfolded, the end of thelocking pin 43 slides along the pin guide surface 312 toward the spurgear formation 121 of the front wheel frame 10.

As the end of the locking pin 43 meets the spur gear formation 121, theslide surface 12 comes into alignment with the pin guide surface 312because the relative rotation of each frame is precisely controlled bythe meshed teeth of the spur gear formations 311 and 121. By carefulconfiguration of the locking pin 43, the pin guide surface 312 and theslide surface, both curved surfaces have a common tangent at thetransition point between the two as the pin guide surface ‘hands-off’the end of the locking pin 43 to the slide surface 12 or vice versa.

Once on the slide surface 12, the locking pin 43 continues towards thegroove section 122 in the front wheel frame 10. When the groove sections313 and 112 align, the spring 44 biases the locking pin 43 into thelocked position with its rounded end against the metal pin 221. Thearcuate opening 123 accommodates the metal pin 221 as the front wheelframe 10 rotates relative to the hinge housing 22.

To collapse the stroller into its configuration, the handle frame 30 isprovided with an unlocking actuator 33 with a pair of manually actuatedtriggers 32 connected by cable to the locking pins 43. The manualtriggers 32 are proximate the grip section of the handle frame 30 forretraction by the user which in turn retracts the locking pins 43 intothe unlocked position (see FIG. 5). The angle between the longitudinalextent of the handle frame 30 and the direction of movement of thelocking pins 43 is kept small and preferably less than 45 degrees.Keeping this angle shallow means the manual force used to retract thetriggers 32 is more directly and efficiently applied to the locking pin43.

With the locking pin in the unlocked position, the stroller can collapseinto the folded configuration in which the front wheel frame 10, therear wheel frame 20, and the handle frame 30 are substantially parallelto each other.

Referring to FIGS. 6, 7 and 8, the braking mechanism of the rear wheelframe 20 is shown in detail. The brake actuator pedal 212 is mounted tothe lower end of the rear wheel frame 20 via pivot axis 214. The spring217 and wedge-shaped end cup 218 act on the brake pedal 212 to providean over-centre mechanism whereby the pedal 212 is biased into an engagedposition or a dis-engaged position. In the engaged position, the rightside locking spigot 215 and the left side locking spigot 213 engage withthe rear wheel hub spline formation 216 to prevent the wheels 211 fromrotating.

Foot actuation of the brake pedal past the balance point of theover-centre mechanism (217 and 218) biases the left and right lockingspigots (213 and 215) out of engagement with the rear hub spline suchthat wheels 211 rotate freely. Brake cable 24 extend between the brakepedal 212 and corresponding pivot mount for the left locking spigot tosynchronise braking of both wheels 211.

The brake pedal 212 is positioned such that it is foot actuated usingthe sole of the foot or shoe only. This avoids any scuffing to the uppersurfaces of any footwear or potential injury for those with open toedfootwear.

Referring to FIGS. 10, 11, 12 and 13, the front wheel assembly 11 of thefront wheel frame 10 is shown in detail. The front wheels 114 arecastors mounted for rotation about vertical axles 116 for steering andmaneuverability of the stroller. A vertical axle mount is inserted intothe lower end of the front wheel frame 10 and held by interference fit.The vertical axles of the rotatable hinge mount 112 are retained in thebore of the vertical axle mount via a cir-clip. The sprung wheel mounts113 pivotally attach to the rotatable hinge mounts via hinge axles 117.Suspension spring 115 acts between the rotatable hinge mount 112 and thesprung wheel mount 113 to provide the front wheels 114 with suspension.It will be appreciated that sprung suspension on the front wheelsimprove the ride quality for the child or toddler and dampen impactloads on the collapsible frame caused by ground irregularities.

Comprises/comprising and grammatical variations thereof when used inthis specification are to be taken to specify the presence of statedfeatures, integers, steps or components or groups thereof, but do notpreclude the presence or addition of one or more other features,integers, steps, components or groups thereof.

The present invention has been defined herein by way of example only.The skilled workers in this field will readily recognise many variationsand modifications which do not depart from the spirit and scope of thebroad inventive concept.

The invention claimed is:
 1. A collapsible stroller, comprising: a front wheel frame, a rear wheel frame; a handle frame; a hinge joint that connects the front wheel frame and the rear wheel frame with the handle frame, wherein a locking element enables the stroller to be converted between folded and unfolded configuration, where in a spur-gear integrally formed with the handle frame meshes with a spur-gear integrally formed with the front wheel frame, further wherein the locking element slides within a two-section groove and where the hinge joint has at least two reinforced bearing surfaces adjacent to the locking element to allow structural loads to be transferable between the reinforced bearing surfaces and the locking element.
 2. The collapsible stroller according to claim 1, wherein the locking element is a metallic locking pin.
 3. The collapsible stroller according to claim 2, wherein the hinge joint has at least two reinforced bearing surfaces adjacent the locking element when in the locked position such that structural loads are transferrable between the reinforced bearing surfaces via the locking element.
 4. The collapsible stroller according to claim 3, wherein at least one of the at least two reinforced bearing surfaces is provided by a metal axle.
 5. The collapsible stroller according to claim 4, wherein another one of the at least two reinforced bearing surfaces is provided by a movable pin element located closely adjacent the metal axle of the front wheel frame and which is configured to move into a load bearing position when the locking pin moves to the locked position and moves away from the load bearing position when the locking pin retracts from the locked position.
 6. A collapsible stroller according to claim 5, wherein the movable pin element extends parallel to the metal axle of the front wheel frame and is guided in an arcuate slot about the front wheel frame axle.
 7. A collapsible stroller comprising: a predominantly polymer handle frame; a predominantly polymer front wheel frame; a predominantly polymer rear wheel frame; a hinge joint connecting the handle frame, the front wheel frame and a locking element at the hinge joint slidingly moveable between an unlocked position in which the handle frame, front wheel frame and rear wheel frame are enabled to mutually rotate into a folded configuration, and a locked position in which the handle, front wheel and rear wheel frames are fixed to each other in an unfolded configuration; wherein the hinge joint comprises a hinge housing of polymer material integrally formed with the polymer rear wheel frame, a spur-gear formation of polymer material integrally formed with the handle frame, the handle frame spur-gear formation configured for rotation about one of the hinge axles within the hinge joint, and a spur-gear formation of polymer material integrally formed with the polymer front wheel frame, the front wheel frame spur-gear formation configured for rotation about the other one of the hinge axles within the hinge joint and meshing with the handle frame spur-gear formation.
 8. The collapsible stroller according to claim 7, wherein the locking element is a metallic locking pin.
 9. The collapsible stroller according to claim 8, wherein the hinge joint has at least two reinforced bearing surfaces adjacent the locking element when in the locked position, such that structural loads are transferrable between the reinforced bearing surfaces via the locking element.
 10. The collapsible stroller according to claim 9, wherein at least one of the at least two reinforced bearing surfaces is a metal axle.
 11. The collapsible stroller according to claim 10, wherein another one of the at least two reinforced bearing surfaces is provided by a movable pin element located closely adjacent the metal axle of the front wheel frame and which is configured to move into a load bearing position when the locking pin moves to the locked position and moves away from the load bearing position when the locking pin retracts from the locked position.
 12. A collapsible stroller according to claim 11, wherein the movable pin element extends parallel to the metal axle of the front wheel frame and is guided in an arcuate slot about the front wheel frame axle. 